Various different high temperature engineering plastics exist that can be used to form different parts and articles. Such polymers include, for instance, polyarylene sulfide polymers. Polyarylene sulfide polymers are strong, have excellent chemical resistance, have high rigidity, and have good resistance to heat such that they can be used in high temperature applications. For example, polyarylene sulfide polymers can be used to replace metal parts at a fraction of the weight. In addition to being lighter, articles made from polyarylene sulfide polymers also produce less noise and are more resistant to chemical attack than many metals.
Polyarylene sulfide polymers are also thermoplastic in nature allowing them to be used in various molding processes, such as injection molding.
For instance, in the past, various molded parts have been produced from a composition containing a polyarylene sulfide polymer combined with glass fibers and an aminosilane. The above composition has proved very successful in producing various products, particularly made via injection molding. The above composition, however, also does have its limitations when used in particular molding processes, such as extrusion blow molding.
For example, when blow molding with fiber reinforced polyarylene sulfide resins, problems have been experienced in controlling and/or obtaining uniform wall thickness during forming of the parison. For instance, during complex blow molding operations, tubular members are formed that are constantly undergoing shape changes. In one application, for example, a parison is extruded in a downward direction while the polymeric composition remains at an elevated temperature. The polymeric composition is extruded through an annular opening or die until a desired length of the parison is obtained. The parison needs to maintain uniform wall thickness while it is being extruded and resist stretching or elongation under only its own weight until a desired length is obtained to begin blow molding. The parison may also be maneuvered for example by a robot during extrusion to change the angular displacement of the tubular form to a specific shape.
The mold closes onto the tubular form once the desired length is attained and a needle is inserted at one end of the closed parison to allow a gas or air to be injected into the tubular form to blow mold the article into its final shape. During the above process, past compositions containing a polyarylene sulfide resin had a tendency to sag during the process and changes the thickness of the parison inadvertently. Sagging is a low shear phenomenon and is affected by the melt strength or melt elasticity of the polymeric composition.
In this regard, the present disclosure is directed to fiber reinforced polymeric compositions containing a polyarylene sulfide polymer that are capable of forming molded parts having a complex shape. More particularly, the present disclosure is directed to a fiber reinforced polyarylene sulfide composition that is more amenable for use in extrusion and blow molding processes for producing parts with complex shapes and enables excellent control of wall thickness.